Combustion systems for heating fluids



April 13, 1965 R. L. JONES ETAL COMBUSTION SYSTEMS FOR HEATING FLUIDS Filed NOV. 18, '.363

1N VENTOR. 90V.

mw NN United States Patent i 3 177,865 CGMBUSTIN SYS'I'MS FR HEATING FLUlDS Robert L. Jones and Howard H. Nichols, Pittsburgh, Pa., assignors to Hazen Engineering Company, Pittsburgh, la., a corporation of Pennsylvania Filed Nov. 18, 1963, Ser. No. 324,572 2 Claims. (Cl. 126-109) This invention relates to new and useful improvements in combustion systems for heating uids, and the present application is a continuation-in-part of application serially numbered 122,591 led July 7, 1961 and now abandoned.

The invention relates to new and useful improvements in combustion systems for heating fluids such as liquids or gases and air and it is among the objects thereof to provide a lluid heater which consists of a combustion air tube surrounded by air under pressure, which tube h as a perforated wall through which the surrounding air 1s forced into a stream of a pre-mix of fuel and air which is ignited to propagate a flame at each of the perforatlons by burning the inspirated pre-mix in the presence of the air that pierces it.

lt is a further object of this invention to utilize a iirst fluid flow tube closed at one end that extends substantially the full length of the perforated burner tube and a second iluid flow tube disposed Within said first tube to deliver the iiuid to be heated to the first tube adjacent the closed end thereof to cause the liquid to ilow through the annular chamber between the iirst and second tube to use. The iiuid ilowing in said annular chamber being heated by the series of burner flames propagated in the annular space between the lirst tube and the said combustion air tube.

lt is a further object of this invention to provide a fuel and air pre-mix chamber at one end of the combustion tube connected to a source of fuel and air having means for igniting the combustible mixture which passes through the annular space between the combustion tube and the iirst fluid dow tube to a waste gas chamber or outlet.

These and other objects of the invention will become more apparent from a consideration of the accompanying drawing in which the single ligure is a side elevational view partially cut away and partially in cross section, of a combustion system for heating uids embodying the principles of this invention.

ln the drawing, the numeral 1 designates a steel jacket or housing of substantially rectangular shape but any other such as cylindrical shape could be employed. The

i heating unit is divided into an air chamber 2 and a waste gas chamber 3 by a partition wall 4, said waste gas chamber having an exhaust stack 5. An air blower 6 supplies air under pressure to the air chamber 2 by ductwork 7 at any desired pressure. Disposed Within the air chamber 2 are a plurality of combustion tubes 8 and 9. Any de-v sired number of such tubes may be employed within the available space of air chamber 2. The tubes S and 9 are provided with anges 10 by which they are attached to the partition wall 4 at one end and they may be suitably supported at their other end if desired or necessary because of their length. The tubes 8 and 9 are open to the waste gas chamber 3 for the escape of products of combustion as indicated by arrows. A pre-mix chamber 11 constituted by a conical shaped housing 12 has its large end disposed in the tubes 8 and 9 to have a sliding tit therewith to allow the combustion air tubes 8 and 9 to expand when heated. A pipe 13 communicates with the air chamber 2 to deliver air under pressure to the premix chamber 11 and a fuel pipe 14 with a valve 14a extends into the chamber 11 to supply a gaseous fuel to the pre-mix chamber 11. A peep site 15 through which the combustion taking place within the combustion tube 3,177,865 Patented Apr. 13, 1965 may be observed is mounted adjacent the pre-mix chamber 11, as shown, and a spark plug 16 or a pilot ame, not shown, is mounted on the conical housing of the combustion chamber, as shown.

The combustion tubes 8 and 9 are provided with perforations 17 and 1-3, respectively, to propagate the llames 19, as will be hereinafter described.

Disposed within the combustion tubes 8 and 9 are Huid flow tubes 20, as shown in tube 8. 'I'he tube 20 has an end closure 21. It is spacedV from the air combustion tube 8 a distance to allow for the propagation of the flame 19 at the burner holes or perforations 17 and if desired, the pressure in the air chamber 2 may be suchvthat the flame 19 plays tire on the tube 20 carrying the liquid to be heated to allow for rapid heating of the liquid.

Disposed within the iiuid ow tube Z0 is a second'lluid flow tube 22, which is open at the end adjacent the closure 21 of tube 20 and is connected to a cold uid header 23 from which the uid, whether air or liquid, ows through the tube 22 into the annular space between the tube 22 `and tube 20 and thence to an outlet 24. Outlet 24 is connected to a fluid flow tube 20a like the tube 20 in which is disposed a smaller tube 22a like the tube 22. As shown by the arrows, the heated uid from tube 20` ows into the tube 20a and passes through the annular tlow passage between the tube 20a and tube 22a to the open end of the latter and it is then conducted through the tube 22a as shown by arrows. In this manner, the fluid may pass through several burners and heater assemblies to increase its temperature before it is delivered to the heated uid header 25.

It is evident that the outlets 24 of the upper heating unit could be connected to a manifold so that a supply of iluid would be heated by a single pass through one or more of the combustion tubes and uid ow assemblies or any number of the fluid heating units could be connected in series to increase the temperature of the iluid as it hows from one assembly to another and linally to a point of use.

It is also apparent that instead of a liquid such as water, pickling iiuids, etc., air or gases can be heated in the same manner.

By regulating the air blower 6, any desired air pressure may be maintained inthe air chamber 2 and this pressure is communicated through the pipe 13 to the premix chamber l1. At ignition, a lean mix is ignited by the spark plug or pilot burner 16 and after ignition, more fuel is added by regulating the valve 14a of the fuel line 14 so that ignition takes place in the combustion air tube where the combustion air pierces the pre-mix as it passes through the annular space between tubes 8 and 20 to the Waste gas chamber 3.

The pressure in air chamber 2 is of a degree to cause the air to pass through the perforations 17 and pierce the preemix thereby inspirating the pre-mix into the cone of air to create a combustible mixture. These pre-mixed cones become ignited beginning from the pre-mix chamber throughout the length of the combustion tube to propagate the ames 19, as shown. By regulating the air pressure, the ame can be lengthened or shortened within limits and even made to play direct on the metal wall of the tube 24) to heat the liquid delivered by the uid flow tube 22 to the space between tube 20 and 22 and thence through the outlet connection 24. Obviously the air in chamber 2 becomes preheated by combustion Vwithin the combustion air tube 8 so that the air forced Y through the perforations is at substantially combustion temperatures when it reaches the burner flames. In this manner, combustion is maintained throughout the entire length of the tube because as the pre-mix within the cornbustion air tube 8 becomes contaminated with the prodenvases ucts of combustion, it also increases in temperature which, together with the preheated air from the perforations 17, consumes any residual combustible fuel or atmosphere as it Hows to the waste gas chamber 3.

Instead of the combustion tubes and the fluid flow tubes being disposed horizontally, as shown in the drawing, they can be disposed vertically and they can of course be arranged in any numbers in cylindrical housings or rectangular shaped ones.

Although one embodiment of the invention has been herein illustrated and described, it will be evident to those skilled in the art that various modifications may be made in the details of construction without departing from the Y principles herein set forth.

We claim: v

1. In a combustion system for heating fluids a pressure chamber for maintaining combustion air under pressure, an assembly comprising a combustion air tube disposed in said chamber having perforations in the wall thereof to direct jets of air from said pressure chamber to the interior of said tube, means delivering to said tube at one end a supply of premixed fuel and air that burns when inspirated into the jets of air entering the tube, the other end of said tube havingta Waste outlet, a first uid 110W tube closed at one end disposed inside of said combustion air tube to provide an annular ow passagef0r the flow of the premixed fuel and air and products of combustion therethrough and to said Waste gas outlet, a second uid flow tube open at one end extending into said iirst fluid tiow tube terminating with its open end adjacent the closed end of said first tube to provide -an annular fluid flow passage between said first fluid flow tube and second iuid ow tube for the iiow of fluid to be heated, and ignition means for firing the premixed fuel and air at the perforations of the combustion air tube.

2. A combustion system for heating uids as set forth in claim 1 together with one or more additional combustion air and iiuid iiow tube assemblies disposed in said air chamber and wherein the fiuid ow tubes are inter-connected to pass heateduid from one uid flow tube assernbiy to another fluid flow tube assembly to be further heated and delivered to a point of use.

References Cited by the Examiner UNTED STATES PATENTS 764,010 7/04 Rowe 126-90 931,565 8/09 Caygill 126-117 2,393,792 1/46 McCollum 126-110 2,462,395 2/49 Heiman 126-110 X JAMES W. WESTHAVER, Primary Examiner. 

1. IN A COMBUSTION SYSTEM FOR HEATING FLUIDS A PRESSURE CHAMBER FOR MAINTAINING COMBUSTION AIR UNDER PRESSURE, AN ASSEMBLY COMPRISING A COMBUSTION AIR TUBE DISPOSED IN SAID CHAMBER HAVING PERFORATIONS IN THE WALL THELREOF TO DIRECT JETS OF AIR FROM SAID PRESSURE CHAMBER TO THE INTERIOR OF SAID TUBE, MEANS DELIVERING TO SAID TUBE AT ONE END A SUPPLY OF PREMIXED FUEL AND AIR THAT BURNS WHEN INSPIRATED INTO THE JETS OF AIR ENTERING THE TUBE, THE OTHER END OF SAID TUBE HAVING A WASTE OUTLET, A FIRST FLUID FLOW TUBE CLOSED AT ONE END DISPOSED INSIDE OF SAID COMBUSTION AIR TUBE TO PROVIDE AN ANNULAR FLOW PASSAGE, FOR THE FLOW OF THE PREMIXED FUEL AND AIR AND PRODUCTS OF 